def previous
import bend-collections-laws-crypto@1.0.0.0/spec/crypto/sha512.bend as Sha512import Base
import bend-collections-laws-crypto@1.0.0.0/src/crypto/sha512/types.bend as T
202def previous(history: List<&2, T.Lane>, lag: Nat) -> T.Lane:
203 nth(history, Nat.sub(lag, 1n))